Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
THERMOMECHANICAL AND RHEOLOGICAL ANALYSIS OF POLYAMIDE 11 UNDER AGEING CONDITIONS IN OFFSHORE FIELDS
Submission Author:
Guilherme Pereira Mota , RJ
Co-Authors:
Guilherme Pereira Mota, Antonio Henrique Monteiro da Fonseca Thomé da Silva, Ana Lúcia Silva, Felipe Moura, Juan Carlos Assis da Silva
Presenter: Juan Carlos Assis da Silva
doi://10.26678/ABCM.ENCIT2022.CIT22-0321
Abstract
Thermoplastics parts are historically used in the oil and gas industry in a large range of successful applications, such as offshore flexible pipes as pressure barrier and outer sheath layers (API17J) for oil and gas production and water and/or gas injection. In onshore application, thermoplastic self-supported pipes are currently used, for instance, in natural gas supply chain. Polyamide 11 or PA-11 is a semi-crystalline thermoplastic polymer largely used in the oil and gas industry given its good overall thermomechanical performance. In offshore fields, as pressure barrier layer in flexible pipes, PA-11 can be exposed to different scenarios, leading to different ageing levels within lifespan (API17TR2). According to API17TR2, there are several typical analytical techniques to monitor the molecular weight of polymeric materials such as osmometry, ebulliometry, viscometry (corrected inherent viscosity, CIV), and size exclusion chromatography. However, the American Petroleum Institute recommends the use of CIV for molecular weight measure. On the other hand, the main disadvantage of these methods is the necessity of one step of sample preparation such as dissolution, extraction, or chromatographic separation increasing, as consequence, the time of analysis. The work presented here investigated PA-11 molecular weight changes considering different ageing levels (corrected inherent viscosity - VIC), based on the correlation between rheological and thermal properties of PA-11. Rheological tests were performed in a Haake rotational rheometer using plate-plate geometry. Frequency sweep tests were performed at temperature of 190ºC, for the different levels of ageing evaluated, in order to determine storage (G´) and loss (G´´) modulus. A Shimadzu DSC (Differential Scanning Calorimetry) and TGA (Thermogravimetric analysis) were used to determine thermal performance of PA-11 under inert media, more specifically crystallinity and mass loss/thermal endurance of PA-11, respectively. Preliminary results shows that there is a relationship between molecular weight obtained in rheological tests and those calculated by correlated inherent viscosity using API 17TR2. Thus, rheological and thermal tests can possibly be used as alternative experiment routes to measure molecular weight for polymer 11 in the absence of correlated inherent viscosity.
Keywords
Polyamides, DSC, TGA, rheological properties, corrected inherent viscosity
